With an aging population and a resulting increase in the relative proportion of persons having issues with mobility who require the use of a wheelchair, there is a need for devices that assist such persons to continue to live in their homes, including assisting them to navigate stairs.
Various devices are known for use in moving persons in wheelchairs up and down interior stairs. For example, U.S. Pat. No. 4,345,669 (24 Aug. 1982; Wheelchair Lift; Noall), discloses such a device.
Such devices are not normally used to deal with external stairs. Rather, it is usual to retro-fit a permanent or semi-permanent ramp to enable the wheelchair user to bypass the stairs. However, such fixed ramps must have a gentle slope and thus require considerable space and material. A maximum slope of 1:12 is recommend for exterior wheelchair ramps. Thus, each one-foot rise requires twelve feet of run in order to provide the desired maximum slope. In many situations, there is inadequate room for a ramp with the desired maximum slope.